Known trimmer constructions comprise cooperating cutting blades that are moved against each other, to cause cutting edges on the cutting blades to interact to effect cutting of material, such as vegetation. In one exemplary form, the separate cutting blades are elongated and have cooperating surfaces that are guided to move against each other to produce a cutting action as the cutting edges thereon are caused to repetitively interact with a scissors-type action. Ideally, the cutting blade surfaces move, one against the other, without excessive binding. Examples of mechanisms for this purpose are described below.
In one design, the cutting blades are operatively connected to a support bar on a frame associated with a drive mechanism, such as an internal combustion engine or an electric motor. A number of bolts are directed through recesses in the cutting blades and are connected to the support bar by threaded fasteners so that the blades are held between the support bar and the heads of the bolts. The bolts are tightened and then released ¼ to ½ turn to allow sufficient clearance between the blades, allowing them to be guided against each other without significant resistance. This mechanism has an advantage that it allows the spacing between the blades to be changed with wear thereof, which increases the clearance to beyond an optimal amount. As the clearance increases over a certain amount, the cutting effectiveness may diminish. The blades may at some point be prone to jamming if and when material wedges between the cooperating surfaces. A problem with this system is that the adjustment must be made by the end user in the field. Some users may find the adjustment process difficult or confusing, whereas others may not wish to take the time necessary to adjust the bolts.
In an alternative design, a rigid spacer may be fixed between a support bar and the bottom cutting blade. A bolt is tightened until the relationship between the support bar and bottom blade is fixed. This space is not adjustable and therefor is fixed as dictated by the configuration of the spacer. Over time the repetitive cutting action of the blades in contact with each other, will cause wear that increases the spacing between the cooperating cutting blade surfaces. Eventually, the clearance between the blade surfaces will be such that the blades are detrimentally movable away from each other to the point that the cutting blades will not effectively sever the material for which they are designed or become jammed by material that is being cut.
Hence, there is a need for an arrangement that at least partially mitigates the above problems. The object of the invention is to provide an improved relating to spacing between cutting blades caused by wear.